Molecular rearrangement of cycloalkadienic compounds



United States Patent 3,432,564 MOLECULAR REARRANGEMENT OF CYCLO- ALKADIENIC COMPOUNDS James Hoekstra, Evergreen Park, Ill., assignor to Universal Oil Products Company, Des Plaines, 11]., a corporation of Delaware No Drawing. Filed Dec. 16, 1966, Ser. No. 602,128 US. Cl. 260-666 7 Claims Int. Cl. C07c /06, 5/24, 5/14 ABSTRACT OF THE DISCLOSURE The molecular rearrangement of cycloalkadienic compounds is effected by treating the compounds with hydrogen in contact with certain catalytic compositions of matter comprising alumina spheres which have been commingled with a platinum-group metal and a sulfurcontaining organic acid at conditions which include a temperature in the range of from about 0' to about 400 C. and a pressure in the range of from about 5 to about 2000 pounds per square inch.

This invention relates to a process for effecting the molecular rearrangement of cycloalkadienic compounds. More particularly, the invention is concerned with a process for effecting the molecular rearrangement of cycloalkadienic compounds in the presence of hydrogen and certain catalytic compositions of matter hereinafter set forth in greater detail to prepare ortho-dialkyl-substituted cycloalkanes.

With the increased use of engines which are liquid propelled, such as rocket engines of the type used for missiles or jet engines of the type used for propelling various types of aircraft, it is essential that the fuels for these engines possess various and sundry desired characteristics. For example, the fuels must perform certain functions in each of the essentially three principal functional parts of the rocket engines. These three parts of a typical rocket engine comprise the thrust chamber, the propellent feed system, and the control system. An ideal rocket fuel must therefore be able to function properly in each of the aforementioned parts; for example, the fuel must burn in a stable and efficient manner in the thrust chamber, must burn to form completely gaseous products When a gas generator propellent expulsion system is employed, as well as being able to cool the thrust chamber, must lubricate the pump parts and must operate the control valve. In addition, fuels which are used to operate jet engines on aircraft must have a low freezing point due to the eX- tremely low temperatures at which jet aircraft operate in the upper atmosphere and at the same time must maintain low viscosity and pour points. Therefore, it is necessary to enhance jet fuels or rocket fuels, the two terms for purposes of this invention being used interchangeably and connoting the same fuel. In this respect, certain hydrocarbons of particular configuration have been found to possess the aforementioned desirable chtaracteristics and therefore may be used as blending materials whereby jet fuels of improved characteristics may be obtained thereby.

It is known that the heat of combustion of hydrocarbons on the basis of volume tends to increase with inhigh gravimetric heat of combustion due to the high hydrogen content of the molecule. However, certain of these paraf'fins are not usable as rocket or jet fuels, specific examples of these being normal paraffins which possess high freezing points in relation to the size of the molecule. As hereinbefore set forth, a low freezing point is a desirable characteristic of a jet or rocket fuel due to the low ambient temperatures in which these particular engines are operated. Another drawback to the use of normal parafiins is that their volumetric heat of combustion is low due to the low density of the molecule. Yet another type of hydrocarbon which is unsuitable for use as this particular type of fuel comprises olefinic hydrocarbons, these compounds being unsuitable because of poor thermal stability.

A particularly suitable type of hydrocarbon which may be used as a jet or rocket fuel comprises cycloalkanes and particularly those which contain certain alkyl substituents thereon. These hydrocarbons possess gravimetric heats of combustion and burning characteristics which are close to those of normal parafiins. In addition to these desirable characteristics, the cycloalkanes also possess lower melting and freezing points than do the corresponding normal paral'fins, as well as having a relatively high thermal stability. Furthermore, the higher density and specific heat of the cycloalkanes are more advantageous in that the greater density of the compounds allows a smaller volume of fuel to be pumped to the engine thereby consuming less fuel to furnish the energy for pumping. Therefore, in view of all of the rigid specifications hereinbefore set forth, the type of fuel which best meets all of the requirements will include dialkyl-substituted, and particularly a compound such as 1,2-diethylcyclohexane. This compound has been found to possess the proper density, the proper volatility, the proper luminosity and a low melting point.

In view of the aforesaid need for jet fuels, it is an object of this invention to provide a process for the preparation of compounds which are particularly utilizable therefor and which are more efficient in operation than some jet fuels already in use.

A particular object of this invention is to provide a process for the molecular rearrangement of certain cycloalkadienic hydrocarbons utilizing a specific type of catalytic composition of matter to effect the aforesaid molecular rearrangement.

In one aspect, an embodiment of this invention resides in a process for the molecular rearrangement of a cycloalkadiene which comprises treating said cycloalkadiene with hydrogen at molecular rearrangement conditions in the presence of a catalyst which has been prepared by commingling alumina particles with a catalytically active amount of a platinum group metal and with a sulfur-containing organic acid and effecting the deposition of such platinum group metal on the surface of said alumina particles, and recovering the resultant product.

A specific embodiment of this invention is found in a process for the molecular rearrangement of cyclodecadiene which comprises treating said cyclodecadiene with hydrogen at a temperature in the range of from about 0 to about 400 C. and at a pressure in the range of from about 5 to about 2000 pounds per square inch in the presence of a catalyst which has been prepared by commingling low density alumina particles with a platinum compound providing from about 0.2. to about 2.0% by weight of platinum and from about 0.3 to about 3.5% by weight of thiomalic acid whereby the deposition of platinum is effected only on the outer surface of said alumina particles and without substan tial penetration thereof, subsequently reducing the composite in an atmosphere of hydrogen at a temperature 3 within the range of from about 90 to about 540 C. and recovering the resultant 1,2-diethylcyclohexane.

Other objects and embodiments will be found in the following further detailed description of this invention.

Of the particular alkyl-substituted cyclohexanes which are useful as fuels for jet engines or as rocket propellent material, the diethylcyclohexanes possess the most desirable characteristics for use as fuels. These compounds possess freeze points below l10 F., and have a low viscosity as well as a high gravimetric heat of combustion. The aforementioned characteristics thus make the diethylcyclohexanes, and particularly 1,2-diethylcyclohexane, a particularly valuable compound for use as a blending agent to prepare jet fuels or rocket propellents which possess the maximum desired characteristics or properties. Therefore, it would be advantageous from a commercial point of view if a process could be found in which alkyl-substituted cyclohexanes could be prepared in an economically attractive process. In this respect, it has now been discovered that alkyl-substituted cycloalkanes and particularly alkyl-substituted cyclohexanes may "be prepared by effecting a molecular rearrangement of the cycloalkadiene in the presence of certain catalytic compositions of matter to obtain the desired product.

Heretofore, it has been known to effect a molecular rearrangement by a process known as the Cope rearrangement. However, this rearrangement is effected in the absence of a catalyst while using relatively high reaction temperatures. The use of these high temperatures which are required to effect the rearrangement in many cases results in side reactions with a concurrent poor yield of the desired product. In contradistinction it has been discovered that a molecular rearrangement of a cycloalkadiene may be effected by utilizing certain catalysts of a type hereinafter set forth in greater detail while effecting the reaction at a relatively low temperature and thereby increase the yield of the desired product. The reaction conditions which are utilized to effect this molecular rearrangement include temperatures which are sub-atmospheric in nature and will lie in a range of from about to about 400 C., preferably in a range of from about 5 to about C. In addition, the reaction is also effected at superatmospheric pressures ranging from about 5 to about 2000 pounds per square inch, said pressure being obtained by the introduction of hydrogen into the reaction zone, said hydrogen entering into the reaction to effect the hydrogenation of the compound to produce the desired product. In addition, it is also contemplated that higher pressures may be utilized and that the hydrogen provide only a partial pressure, the remainder of the pressure being provided for by the introduction of an inert gas such as nitrogen into the reaction zone.

The catalytic compositions of matter which are used to effect the molecular rearrangement of the cycloalkadiene in the presence of hydrogen comprises a catalyst in which aluminous spheres have been impregnated with a platinum group metal compound and a sulfur-containing organic acid.

As employed in the present specification, the term metallic component is intended to connote those components of the catalyst which are employed for the catalytic activity as distinguished from that part of the catalyst herein referred to as the refractory inorganic oxide, and which is employed for the purpose of supplying suitable carrier material or support, for the catalytically active metallic components. Although it is not considered to be a limiting feature of the present invention, it is preferred that the catalytically active metallic component, or components, be composited with a refractory inorganic oxide carrier material which has an apparent bulk density of less than about 0.4 gram per cc. Preferred refractory inorganic oxides, for as the carrier material, possess an apparent bulk density within the range of frpm about 0.15 to about 0.35 gram per cc. The catalytically active metallic com ponents, composited with the refractory inorganic oxide carrier material, may be one or more of the following: vanadium, chromium, molybdenum, tungsten, mixtures of the iron-group and platinum-group of the Periodic Table, copper, silver and gold. A particular metal which may be used in and of itself, or in combination of any of the foregoing metals. The catalyst of the present invention may comprise a metallic component selected from the Groups V-A, VI-A and VIII of the Periodic Table. Thus, the metallic component may comprise the following: platinum, palladium, iridium, ruthenium, rhodium, iron, c0- balt, nickel, copper, vanadium, tungsten, molybdenum, silver, gold or various mixtures thereof such as platinum, iron, platinum-cobalt, platinum-nickel, palladium-iron, palladium-cobalt, palladium-nickel, platinum-palladium, palladium-cobalt-copper, platinum-palladium-cobalt, copper-cobalt-nickel-platinum, etc. It is to be understood that the catalytic activity, stability and other characteristics of the catalyst which is used to effect the molecular rearrangement of a cycloalkadiene may vary from catalyst to catalyst and that many of the particular catalytic composites do not necessarily yield equivalent results when compared with a catalyst comprising one or more different metallic components, or when utilized under varying conditions in different processes. Although the precise manner in which the catalytically active metallic component, such as platinum, is associated with the carrier material is not known with absolute certainty, it is believed that the platinum, or other metallic component, enters into a combination with the carrier material. Therefore, it is understood that the use of the term platinum or metallic component, :for example, connotes platinum or other metallic components existing within the carrier material in a combined form and/or in the elemental state.

The catalytic composite which is used in the process of the present invention, the method of the preparation of which is hereinafter set forth in greater detail, utilizes a refractory inorganic oxide as the carrier material for the active metallic components hereinbefore set forth. One desired physical characteristic, for example, is that high temperatures do not apparently affect the capablity of the material to function as desired. The refractory inorganic oxide carrier material, for utilization in the catalyst may be manufactured by any suitable method including separate, successive, do-precipitation means of manufacture when comprising two or more individual inorganic oxides. The carrier material may comprise naturally-occurring substances such as clays or earths, and may or may not be activated prior to use by one or more treatments including drying, calcining, steaming or treatments with various reagents, etc. The catalytic composite will preferably make use of an alumina-containing refractory inorganic oxide carrier material; as employed herein, the term alumina is intended to include porous aluminum oxide in various states of hydration. In addition to alumina, other refractory inorganic oxides may be employed, either in conjunction with, or instead of, the alumina. Other suitable inorganic oxides include silica, boria, thoria, titania, zirconia, hafnia and mixtures of two or more. The incorporation of any of the foregoing refractory in-organic oxides, in conjunction with the alumina, is generally dependent upon the desire to add thereto certain physical and/or chemical characteristics required by the particular application for which the catalytic composite is intended. Such other refractory inorganic oxides, for example, silica, will be present within the carrier material in an amount within the range of about 0.5% to about 25.0% by weight thereof, based upon the final weight of the carrier. Intermediate quantities are preferred and will lie within the range of from 1.0% to about 10.0% by weight. The carrier material may take the form of any desired shape such as spheres, pills, extrudates, granules, cakes, briquettes, rings, etc. The preferred form is the sphere, and spheres may be continuously manufactured by the well-known oil drop method: this method is described in detail in U.S. Patent No. 2,620,314 issued to James Hoekstra. In the interest of simplicity and clarity, the following discussion will generally refer to the use of alumina as the refractory inorganic oxide carrier material.

Where desired, halogen may be combined with the alumina and the catalytically active metallic components, and may be added thereto in any suitable manner either before, or after the incorporation of the active metallic components. The addition of the halogen is generally accomplished through the use of an acid such as hydrogen fluoride and/or hydrogen chloride, or volatile salt such as ammonium fluoride and/or ammonium chloride, and the halogen may be combined with the alumina during the preparation of the latter. In still another method of manufacture, the halogen may be composited with a refractory oxide during the impregnation thereof with the catalytically active metallic components. Thus, where the alumina is prepared from an alumina hydrosol having an aluminum to chloride weight ratio of about 1:3, the use of such method permits the incorporation of chloride where the latter is desired as the halogen component.

Regardless of the particular refractory inorganic oxide carrier material employed, during or prior to the addition of the metallic component, such as platinum, the preformed inorganic oxide particles, such as alumina, are treated with a sulfur-containing organic acid. The selected sulfurized acid may be added to the alumina particles as a separate solution just prior to commingling with the metallic component; however, for ease in handling and metering, the organic acid is preferably admixed, in the requisite quantity, with the water-soluble compound of the intended catalytically active metallic component, and the resulting impregnating solution combined with the carrier material. With respect to platinum, suitable watersoluble compounds for utilization in the impregnating solution include chloroplatinic acid, chloroplatinous acid, platinous chloride, platinic chloride, etc. Where the catalytic composite is intended to contain other metallic components, such as those hereinbefore set forth, the composite may be prepared by commingling water-soluble compounds of these components, particularly the nitrates, sulfates, chlorates, chlorides, carbonates, and immersing the particles of the carrier material therein, followed by heating to form the corresponding oxides of the metallic components.

The sulfur-containing organic acid utilized in the method of the present invention is preferably a thio or mercapto carboxylic acid, as for example, thiomalic acid, thioglycolic acid, mercaptopropionic acid, etc.

The quantity of the organic acid, or derivative thereof, to be employed in admixture with the water-soluble compound of the catalytically active metallic component and the carrier material, is generally based upon the Weight of such carrier material. The amount of organic acid employed is within the range of about 0.1% to 10.0% by weight. An intermediate concentration of the organic acid, and/ or its derivative is preferred and is within the range of from about 0.3% to about 3.5% by weight, based upon the weight of the carrier material.

The quantity of the catalytically active metallic components is based upon the volume of the carrier material to be combined therewith and is calculated on the basis of the elemental metal, notwithstanding that the metallic component may exist in some combined complex form, or in the elemental state. Thus, with respect to platinumgroup metals, the platinum will be present in an amount of from about 0.05% to about 5.0% by weight based upon the weight of the carrier material. The preferred range of the concentration of the platinum component, dictated by economic considerations, is from about 0.2% to about 2.0% by weight based on the weight of the carrier material. The other metallic components, either in conjunction with, or instead of the platinum component,

will be present in an amount of from about 0.01% to about 5.0% by weight based on the weight of the carrier material employed.

As indicated hereinbefore, the organic sulfurized acid may be admixed with the water soluble compound of the catalytically active metallic component, or components, or mixed with the alumina prior to the addition of the metallic component thereto. In any case, it is an essential feature that the metallic component be not combined with the alumina prior to the addition of the sulfur containing organic acid. Basic impregnation in preparing the improved catalyst is avoided, in that the commingling of the refractory inorganic oxide, the catalytically active metallic component and the organic acid is accomplished in the absence of substances and reagents of a highly alkalinous nature, particularly including ammonia and other nitrogenous compounds, alkali metal compounds, etc. It has further been found that the catalytic composite is adversely afiected when contacted with a nitrogencontaining gas during the final high temperature stages of the manufacture thereof.

In describing the methods of manufacturing the catalytic composite it is understood that the same is not considered to be unduly limited to the particular catalytic composite described. The catalyst, in one example, is prepared by initially forming alumina spheres, f -inch to about A -inch in diameter, from an aluminum chloride hydrosol having an aluminum chloride weight ratio of about 1.25. The alumina spheres are continuously prepared by passing droplets of the hydrosol into an oil bath maintained at an elevated temperature, retaining the droplets within the oil until the same set into hydrogel spheroids. The spheroids are dried at a temperature of from about 200 F. to about 800 F., and thereafter subjected to a calcining treatment at a temperature of from about 800 F. to about 1200 F. An impregnating solution of chloroplatinic acid is prepared by diluting 18 ml. of a stock solution having the concentration of 0.0628 gram of platinum per milliliter to about 500 milliliters with water. When utilized with the approximately grams of the alumina spheres, this concentration of the chloroplatinic acid solution will yield a final composite having about 0.75% by weight of platinum, based on the weight of the spherical alumina carrier material. The chloroplatinic acid solution is then commingled with about 2.6 grams of thiomalic acid, or about 1.7% by weight based upon the weight of the spheres. The resulting mixture of thiomalic acid, chloroplatinic acid and alumina spheres is evaporated to dryness in a rotating drier at a temperature of about 210 F. When the spheres appear visually dry, usually in about two to about eight hours, the impregnated spheres are subjected to a reducing treatment, preferably in an atmosphere of hydrogen, while increasing the temperature to a level within the range of from about 200 F. to about 1000 F., maintaining the elevated temperature for about two hours. If desired, the catalyst may be subjected to an oxidation treatment at elevated temperature, or to high temperature calcination in an atmosphere of air prior to the reducing treatment.

While the discussion of the use of the products of this invention which has been previously set forth is directed mainly to the particular compound, namely, 1,2-diethylcyclohexane, it is also contemplated with in the scope of this invention that other cycloalkadienic compounds may also undergo molecular rearrangement in the presence of the catalyst hereinbefore set forth. For example, 1,5- cyclododecadiene, 1,5 cyclotetradecadiene, 1,5 cyclohexadecadiene, 1,5,9-cyclodecatriene, etc., may be used as starting materials to prepare 1,2-diethylcycloctane, 1,2- diethylcyclodecane, 1,2 diethyldodecane, triethylcyclohexane, etc. However, when effecting the molecular rearrangement of the cycloalkadienic hydrocarbons other than 1,5-cyclodecadiene it is contemplated that reaction temperatures greater than those hereinbefore set forth, that is higher than about 0 to 20 C. must be used. For

example, the rearrangement of 1,5,9-cycldecatriene to form triethylcyclohexane in the presence of the aforementioned catalytic compositions of matter will require a reaction temperature of from about 200 to about 400 C. to effect said rearrangement. Likewise, the molecular re- !arrangement of 1,5-cyclododecadiene to form 1,2-diethylcyclooctane would also require a like temperature range. When utilizing these high temperature ranges it is desirable to use a relatively low hydrogen pressure, that is, below about 50 pounds per square inch in order to avoid hydrogenating all of the polyene before the molecular rearrangement can be effected.

The process of this invention may be effected in any suitable manner and may comprise either a batch or continuous type operation. For example, when a batch type operation is used, a quantity of the starting material comprising the cycloalkadiene may be charged to an appropriate apparatus, such as for example, a rotating or stirred autoclave. The autoclave will also contain the particular catalyst which is to be used. The autoclave is sealed and brought to the desired operating temperature by means of an icebath or any other means known in the art whereby subatmospheric temperatures may be attained, said other means also include cooling coils, etc. Following this, hydrogen is pressed in until the desired pressure is reached. If so desired, the above mentioned procedure may be modified by placing the catalyst in the reactor, cooling to the desired temperature, charging in hydrogen until the desired pressure is reached and thereafter charging the feed stock to the reactor. Upon completion of the desired residence time, which may be in a range of from about 0.5 up to about 16 hours in duration, the hydrogen feed is discontinued, the reactor is allowed to warm to room temperature and the excess pressure is vented. The reaction product is recovered and separated from the catalyst and thereafter subjected to conventional means for separation and purification, the separation means including fractionation under reduced pressure, fractional crystallization, etc.

It is also contemplated within the scope of this invention that the process described herein may be effected in a continuous manner of operation. When such a manner of operation is used, a reactor which contains the desired catalytic compositions of matter is maintained at the proper operating conditions of temperature and pressure. The cycloalkadiene is continuously charged to this reactor as is the hydrogen which is necessary to provide the desired pressure. As hereinbefore set forth, it is also possible to utilize an inert gas such as nitrogen to provide a partial pressure for the desired operating pressure range. Upon completion of the desired residence time, the reactor efiluent is continuously withdrawn and subjected to separation means whereby any unreacted starting material and/or side products are separated from the desired dialkyl-substituted cycloalkane, the unreacted starting material being recycled to form a portion of the feed stock. Inasmuch as the catalyst is solid in nature, a preferred method of effecting a continuous manner of operation is by utilizing a fixed bed type of operation in which the catalyst is suspended as a fixed bed in the reactor and the cycloalkadiene is passed through said bed in either an upward or downward flow. Other types of operations which are adaptable to this process include the moving bed type of operation in which the catalyst and the reactant pass either concurrently or countercurrently to each other and a slurry type of operation in which the catalyst is carried into the reactant as a slurry in the feed stock.

The following examples are given to illustrate the process of the present invention which, however, are not intended to limit the generally broad scope of the present invention in strict accordance therewith.

Example I In this example, a catalyst was prepared by impregnating alumina spheres which had been ground and sieved to a 40-100 mesh with an aqueous solution of chloroplatinic acid in an amount sufficient to yield a catalyst containing 0.75% by weight of platinum based on the alumina. In addition, the platinum impregnation was carried out in the presence of thiomalic acid, the latter being present in a ration of 3 moles of thiomalic acid per mole of chloroplatinic acid. After impregnation, the spheres were evaporated to dryness in a rotating dryer at a temperature of about C. Thereafter while gradually increasing the temperature level of the dryer to 510 C., the catalyst was subjected to an atmosphere of hydrogen for a period of about 1.5 hours.

Following this, 6.5 cc. of the catalyst prepared according to the above paragraph was placed in a reactor consisting of a 12" length of outside diameter stainless steel tubing, said reactor being immersed in a water bath so that the temperature of the reactor was maintained at 5 C. A 20% by weight mixture of cyclodecadiene in cyclohexane at a rate of 8 cc. per 'hour was passed over the catalyst bed along with hydrogen at a rate of 2.5 standard cubic feet per hour, the pressure of the reactor being maintained at about 750 pounds per square inch. Upon completion of the residence time, the reaction mixture was recovered and subjected to analysis. It was found that there was recovered 14% 1,2-diethylcyclohexane.

Example II In this example, a catalyst similar to that prepared in Example I above, that is, impregnation of alumina spheres with an aqueous solution of chloroplatinic acid and thiomalic acid containing 3 moles of thiomalic acid per mole of chloroplatinic acid sufficient to yield a catalyst containing 0.75 weight percent of platinum is dried and calcined at a temperature of about 510 C. for a period of 1.5 hours in an atmosphere of hydrogen. The catalyst is placed in a reactor which is immersed in a water bath containing ice sufiicient to reduce the temperature of the reactor to about 5 C. Hydrogen pressure and flow rate are established at 750 pounds per square inch and 2.5 standard cubic feet per hour. Following this, the charge pump is started and a feed comprising cyclododecadiene at a rate of 8 cc. per hour is charged to the reactor. After a period of about 8 hours, the reaction is terminated and the product recovered. Analysis of the reaction product will disclose the presence of 1,2-diethylcyclooctane.

Example III In order to illustrate the necessity for utilizing a catalyst of the particular composition herein described, another experiment was run in which alumina spheres were impregnated with a solution of chloroplatinic acid in an amount sufficient to deposit 0.75 weight percent of platinum on the alumina spheres followed by impregnation with lithium nitrate. The catalyst was then dried and calcined at a temperature of 510 C. in a hydrogen atmosphere for a period of 1.5 hours.

The catalyst prepared according to the above paragraph was placed in a reactor similar to that set forth in the above example. The reactor was placed in a bath provided with a cold glycol circulated in the cooling coil and the temperature adjusted to 5 C. Hydrogen pressure and flow rate were established at 750 pounds per square inch and 2.5 standard cubic feet per hour. Following this, a feed stock of cyclodecadiene was charged to the reactor at a rate of 8 cc. per hour. Upon completion of the desired residence time, the reaction was discontinued and the product subjected to analysis. It was discovered that no 1,2-diethyl cyclohexane had been obtained, the product being mainly cyclodecane.

I claim as my invention:

1. A process for the molecular rearrangement and hydrogenation of a cycloalkadiene containing from about 10 to about 16 carbon atoms in the ring which consists in treating said cycloalkadiene with hydrogen at reaction conditions which include a temperature in the range of from about 0 to about 400 C. and a pressure in the range of from about 5 to about 2000 pounds per square inch, in contact with a catalyst which has been prepared by commingling alumina particles with a catalytically active amount of a platinum-group metal and a sulfur-containing organic acid and eifecting the deposition of said platinumgroup metal on the surface of said alumina particles, and recovering the resultant diethyl substituted cycloalkane.

2. The process as set forth in claim 1, further characterized in that said alumina particles comprise a low density alumina.

3. The process as set forth in claim 1, further characterized in that said sulfur-containing organic acid comprises thiomalic acid.

4. The process as set forth in claim 1, further characterized in that said platinum group metal comprises a platinum compound.

5. The process as set forth in claim 4, further characterized in that the catalyst contains said platinum compound in an amount providing from about 0.2 to about 2.0% by weight of platinum based on the weight of the alumina particles.

6. The process as set forth in claim 1, further characterized in that said cycloalkadiene comprises cyclodecadiene and said product comprises 1,2-diethylcyclohexane.

7. The process as set forth in claim 1, further characterized in that said cycloalkadiene comprises cyclododecadiene and said product comprises 1,2-diethylcyclooctane.

References Cited UNITED STATES PATENTS 2,960,551 11/ 1960 Feller 260683.2 3,071,364 1/1963 Bailey 260-666 3,326,909 6/1967 Perry 260-666 3,336,386 8/1967 Dovell 260666 3,352,938 11/1967 Plonsker et al 260-6832 3,352,939 11/1967 Breckotf et a1 260-6832 OTHER REFERENCES Untch et al.: J. Amer. Chem. Soc., 87, pp. 4501-6, 1965, [Book in Technical Library].

DELBERT E. GANTZ, Primary Examiner. V. OKEEFE, Assistant Examiner. 

